QIdentityProxyModel: add setHandleSourceDataChanges(bool)

Some sub-classes have special handling of source model data changes,
they relied on disconnecting the connections to the _q_*layout* slots
in the private class using the SLOT macro. This isn't possible any more
after the recent port to PMF connects.

Sub-classes resorting to using private API is a clear sign some
functionality is missing from the public API, so a cleaner solution for
this issue is adding this setter which enables sub-classes to tell
QIdentityProxyModel to leave handling of the dataChanged signal to them.

Similar to commit 675b4f63feab7c81c75e49f6dea82a39dd18f489 (but
this should be the last one needed).

[ChangeLog][QtCore][QIdentityProxyModel] Added
setHandleSourceDataChanges(bool) method to allow sub-classes to
indicate to QIdentityProxyModel that they will handle source model
data changes on their own. Also added a getter,
isHandleSourceDataChanges().

Task-number: QTBUG-127959
Change-Id: Id8f567c330e4ee834940a62b6497d8cbb8ba4a46
Reviewed-by: Axel Spoerl <axel.spoerl@qt.io>
(cherry picked from commit 5a31800d41273a14436c543438a142562f74f857)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>

src/corelib/itemmodels/qidentityproxymodel.cpp

@@ -331,12 +331,15 @@ void QIdentityProxyModel::setSourceModel(QAbstractItemModel* newSourceModel)
                                     &QIdentityProxyModelPrivate::sourceModelAboutToBeReset),
             QObjectPrivate::connect(m, &QAbstractItemModel::modelReset, d,
                                     &QIdentityProxyModelPrivate::sourceModelReset),
-            QObjectPrivate::connect(m, &QAbstractItemModel::dataChanged, d,
-                                    &QIdentityProxyModelPrivate::sourceDataChanged),
             QObjectPrivate::connect(m, &QAbstractItemModel::headerDataChanged, d,
                                     &QIdentityProxyModelPrivate::sourceHeaderDataChanged),
         };
 
+        if (d->m_handleDataChanges) {
+            d->m_sourceModelConnections.emplace_back(
+                QObjectPrivate::connect(m, &QAbstractItemModel::dataChanged, d,
+                                        &QIdentityProxyModelPrivate::sourceDataChanged));
+        }
         if (d->m_handleLayoutChanges) {
             d->m_sourceModelConnections.emplace_back(
                 QObjectPrivate::connect(m, &QAbstractItemModel::layoutAboutToBeChanged, d,
@@ -355,7 +358,7 @@ void QIdentityProxyModel::setSourceModel(QAbstractItemModel* newSourceModel)
 
     If \a b is \c true, this proxy model will handle the source model layout
     changes (by connecting to \c QAbstractItemModel::layoutAboutToBeChanged
-    and \c QAbstractItemModel::layoutChanged singals).
+    and \c QAbstractItemModel::layoutChanged signals).
 
     The default is for this proxy model to handle the source model layout
     changes.
@@ -381,6 +384,36 @@ bool QIdentityProxyModel::handleSourceLayoutChanges() const
     return d_func()->m_handleLayoutChanges;
 }
 
+/*!
+    \since 6.8
+
+    If \a b is \c true, this proxy model will handle the source model data
+    changes (by connecting to \c QAbstractItemModel::dataChanged signal).
+
+    The default is for this proxy model to handle the source model data
+    changes.
+
+    In sub-classes of QIdentityProxyModel, it may be useful to set this to
+    \c false if you need to specially handle the source model data changes.
+
+    \note Calling this method will only have an effect after calling setSourceModel().
+*/
+void QIdentityProxyModel::setHandleSourceDataChanges(bool b)
+{
+    d_func()->m_handleDataChanges = b;
+}
+
+/*!
+    \since 6.8
+
+    Returns \c true if this proxy model handles the source model data
+    changes, otherwise returns \c false.
+*/
+bool QIdentityProxyModel::handleSourceDataChanges() const
+{
+    return d_func()->m_handleDataChanges;
+}
+
 void QIdentityProxyModelPrivate::sourceColumnsAboutToBeInserted(const QModelIndex &parent, int start, int end)
 {
     Q_ASSERT(parent.isValid() ? parent.model() == model : true);

src/corelib/itemmodels/qidentityproxymodel.h

@@ -45,10 +45,12 @@ public:
     bool moveColumns(const QModelIndex &sourceParent, int sourceColumn, int count, const QModelIndex &destinationParent, int destinationChild) override;
 
     bool handleSourceLayoutChanges() const;
+    bool handleSourceDataChanges() const;
 
 protected:
     QIdentityProxyModel(QIdentityProxyModelPrivate &dd, QObject* parent);
     void setHandleSourceLayoutChanges(bool);
+    void setHandleSourceDataChanges(bool);
 
 private:
     Q_DECLARE_PRIVATE(QIdentityProxyModel)

src/corelib/itemmodels/qidentityproxymodel_p.h

@@ -64,6 +64,7 @@ public:
 
 private:
     bool m_handleLayoutChanges = true;
+    bool m_handleDataChanges = true;
     QVarLengthArray<QMetaObject::Connection, 18> m_sourceModelConnections;
 };
 

tests/auto/corelib/itemmodels/qidentityproxymodel/tst_qidentityproxymodel.cpp

@@ -37,6 +37,7 @@ class IdentityProxyModel : public QIdentityProxyModel
 public:
     // The name has to be different than the method from the base class
     void setHandleSLC(bool b) { setHandleSourceLayoutChanges(b); }
+    void setHandleSDC(bool b) { setHandleSourceDataChanges(b); }
 };
 
 class tst_QIdentityProxyModel : public QObject
@@ -65,6 +66,7 @@ private slots:
     void createPersistentOnLayoutAboutToBeChanged();
 
     void testSetHandleLayoutChanges();
+    void testSetHandleDataChanges();
 
 protected:
     void verifyIdentity(QAbstractItemModel *model, const QModelIndex &parent = QModelIndex());
@@ -541,12 +543,29 @@ void tst_QIdentityProxyModel::testSetHandleLayoutChanges()
 
     proxy.setSourceModel(nullptr);
 
-    // Disable handling (connecting to layotu signals) of source model layout changes
+    // Disable handling (connecting to layout signals) of source model layout changes
     proxy.setHandleSLC(false);
     proxy.setSourceModel(&model);
     for (const auto &m : layoutSignals)
         QVERIFY(!model.isConnected(m));
 }
 
+void tst_QIdentityProxyModel::testSetHandleDataChanges()
+{
+    const auto signal = QMetaMethod::fromSignal(&QAbstractItemModel::dataChanged);
+
+    DataChangedModel model;
+    IdentityProxyModel proxy;
+    proxy.setSourceModel(&model);
+    QVERIFY(model.isConnected(signal)); // Connected by default
+
+    proxy.setSourceModel(nullptr);
+
+    // Disable handling (connecting to data signals) of source model data changes
+    proxy.setHandleSDC(false);
+    proxy.setSourceModel(&model);
+    QVERIFY(!model.isConnected(signal));
+}
+
 QTEST_MAIN(tst_QIdentityProxyModel)
 #include "tst_qidentityproxymodel.moc"